Absolute stability of feedback systems independent of internal point delays

The absolute stability, independent of the delays, of time-delay systems ith non-commensurate internal point delays for any non-linearity satisfying a standard time positivity inequality is discussed. That property holds if an associate delay-free system is absolutely stable and the size of the delayed dynamics is sufficiently small. The results are obtained for non-linearities belonging to sectors [0, k] and [h, k+h], k≥0 and are based o a parabola test type.